The field of electromechanical memory and switching devices, in particular the field of micro- and nano-electromechanical devices, has become a field of high research activity and technological interest. The capability of storing multi-bit information is one of the challenges in memory technologies. It provides a way to increase the memory density per volume and may pave the way for an improved design on the system level with higher memory density at lower cost. Efforts have been made to develop non-volatile memory devices with reliable data storage at low cost. Among many kinds of memory devices, flash memories which employ a floating gate structure with two programmable charge states are used, wherein their basic operation is based on charge trapping in a floating gate. Nevertheless, flash technology seems to be limited in scaling as charge leakage increases and charge separation becomes increasingly difficult upon scaling down the device dimensions.
US 2013/0321064 A1 discloses a single-molecule switching device. A tunneling current is applied across a tunneling junction, wherein the tunneling junction includes an endohedral fullerene that includes a fullerene cage and a trapped cluster. One or more internal motions of the trapped cluster are excited because of the tunneling current. The conductance of the endohedral fullerene is based on the one or more excited internal motions. One or more electronic processes are controlled based on the changed conductance of the endohedral fullerene.
The current modulation is based on a rotational change of the trapped cluster inside the fullerene cage. In order to induce this rotational change a higher bias potential must be applied. The rotational change is caused by a larger tunneling current through the endohedral fullerene. Therefore, a bias-based switching is disclosed.